The oldest track about the existence of animals, at least 100 million years before the so-called Cambrian explosion – 540 million years ago – was found by American researchers, reports today "Nature Ecology & Evolution"
The study, by Gordon Love of the Department of Earth Sciences at the University of California Riverside (UCR), indicates that the finding of a molecular fossil suggests that sponges live 100 million years prior to the ocean. Cambrian fossil animals when the sudden occurrence of multicellular macroscopic organisms occurred
According to the article published in the British magazine, the experts sought, instead of locating fossils of organisms, molecular signals about the existence of animal life, called biomarkers, of about 660-635 million years.
In ancient rocks of Oman, Siberia and India, scientists discovered compounds that were produced by sponges, considered the earliest animal life form on the planet.
"Molecular fossils are important for following the first animals, because the first sponges are probably very small, do not contain a skeleton and have not left a well-preserved or easily identifiable fossil record as a record," said the lead author of the study, Alex Zumberge . "We are looking for distinctive and stable biomarkers for the existence of sponges and other first animals," he added.
The identified biomarker (a steroid compound named metilstigmastane-26) has a unique structure known to be synthesized by certain modern sponge species, demosponjas (invertebrates).
"This steroid biomarker is the first evidence that demosponge, and therefore multicellular animals, thrived in the ancient seas at least 635 million years ago," adds Zumberge.